首先 ， 先開啟部落格園的首頁 -> 我的部落格-> 管理-> 設定 ->  找到頁面定製CSS程式碼然後貼上下文程式碼

/*
 程式碼高亮開始，使用了一個叫Monokai Sublime的黑色主題面板，直接拿過來還不行，有一些樣式衝突，還要自己稍微改一些地方
Monokai Sublime style. Derived from Monokai by noformnocontent http://nn.mit-license.org/
*/
pre {
/*控制程式碼不換行*/
    white-space: pre;
    word-wrap: normal;
}
.cnblogs
 
-markdown .hljs {
    display: block;
    overflow-x: auto;
    padding: 0.5em;
    background: #23241f !important;
    color: #FFF;
    white-space: pre;
    word-break: normal;
}

.hljs,
.hljs-tag,
.hljs-subst {
  color: #f8f8f2;
}

.hljs-strong,
.hljs-emphasis {
  color: #a8a8a2;
}

.hljs-bullet,
.hljs
 
-quote,
.hljs-number,
.hljs-regexp,
.hljs-literal,
.hljs-link {
  color: #ae81ff;
}

.hljs-code,
.hljs-title,
.hljs-section,
.hljs-selector-class {
  color: #a6e22e;
}

.hljs-strong {
  font-weight: bold;
}

.hljs-emphasis {
  font-style: italic;
}

.hljs-keyword,
.hljs-selector-tag,
.hljs-name,
.hljs
 
-attr {
  color: #f92672;
}

.hljs-symbol,
.hljs-attribute {
  color: #66d9ef;
}

.hljs-params,
.hljs-class .hljs-title {
  color: #f8f8f2;
}

.hljs-string,
.hljs-type,
.hljs-built_in,
.hljs-builtin-name,
.hljs-selector-id,
.hljs-selector-attr,
.hljs-selector-pseudo,
.hljs-addition,
.hljs-variable,
.hljs-template-variable {
  color: #e6db74;
}

.hljs-comment,
.hljs-deletion,
.hljs-meta {
  color: #75715e;
}

.cnblogs_code {
    background-color: rgba(245, 245, 245, 0.05);
}

#AjaxHolder_UpdatePanel1, #AjaxHolder_PostComment_divCommnentArea, #profile, .entrylist, .gallery {
    background: none repeat scroll 0 0 rgba(255, 255, 255, 0.24);
    border-radius: 7px;
    box-shadow: 1px 1px 2px #A7A8AD;
    margin: 0 0 15px 0;
    min-height: 200px;
    overflow: hidden;
    padding: 0 15px;
    text-overflow: ellipsis;
    word-break: break-all;
}


#home {
    margin: 0 auto;
    width: 80%;/*原始65*/
    min-width: 980px;/*頁面頂部的寬度*/
    background-color:rgba(185, 171, 171, 0.29);
    padding: 30px;
    margin-top: 50px;
    margin-bottom: 50px;
    box-shadow: 0 2px 6px rgba(100, 100, 100, 0.3);
}


body {
    background-repeat: no-repeat;  
    background: rgba(12, 100, 129, 0) url('http://images.cnblogs.com/cnblogs_com/LYFmobai/1353819/o_you.jpg') fixed;
    background-position: 100%  50%; 
    background-size: 50% auto;
}


#blogTitle {
    height: 100px;  /*高度*/
    clear: both;
    background-color: rgba(245, 245, 245, 0);
}
#blogTitle h1 {
    font-size: 36px;
    font-weight: bold;
    line-height: 1.8em;/*原始 1.6em*/
    margin-top: 10px;/*原始 15px */
    color: #548B54;
}
#blogTitle h2 {
    font-weight: normal;
    font-size: 17px;/*原始 16px ；font-size: 1.0rem;*/      
    line-height: 1.8;
    color: #FFFFFF;
    font-weight: bold;
    text-align: right;
    float: right; 
}
#navigator{
    background-color:rgba(59, 181, 153, 0);
}
#navList a:link, #navList a:visited, #navList a:active{
    color: rgba(29, 15, 15, 0.53);
    font-size: 18px;
    font-weight: bold;
}

#navList a:hover {
    color: white;
    background-color: rgba(52, 52, 52, 0.09);
    text-decoration: none;
    text-shadow: 0px 0px 0px #19d427;
}

.blogStats{
    color: #eee;
}
.postTitle {
    border-left: 8px solid rgba(41, 162, 56, 0.56);
    margin-left: 10px;
    margin-bottom: 10px;
    font-size: 20px;
    float: right;
    width: 100%;
    clear: both;
}
.postTitle a:link, .postTitle a:visited, .postTitle a:active {
    color:rgba(16, 25, 16, 0.43);
    transition: all 0.4s linear 0s;
}
.postTitle a:hover {
    margin-left: 30px;
    color: #0f3647;
    text-decoration: none;
}
.postCon {
    float: right;
    line-height: 1.5em;
    width: 100%;
    clear: both;
    padding: 10px 0;
}

.day .postTitle a {
    padding-left: 10px;
}
.day {
    background: rgba(255, 255, 255, 0);
}
/*文章附加資訊*/
.postDesc {   
    background: url(images/posted_time.png) no-repeat 0 1px;
    color: #757575;
    float: left;
    width: 100%;
    clear: both;
    text-align: left;     
    font-family: "微軟雅黑" , "宋體" , "黑體" ,Arial;
    font-size: 13px;
    padding-right: 20px;/*5px  padding-left: 90px;posted 發表時間左邊距離*/
    margin-top: 20px;
    line-height: 1.8;
    padding-bottom: 35px;
}

.newsItem, .catListEssay, .catListLink, .catListNoteBook, .catListTag, .catListPostCategory, 
.catListPostArchive, .catListImageCategory, .catListArticleArchive, .catListView, 
.catListFeedback, .mySearch, .catListComment, .catListBlogRank, .catList, .catListArticleCategory ,#blog-calendar
{
    background: rgba(255, 255, 255, 0.5);
    margin-bottom: 35px;
    word-wrap: break-word;
}

.CalTitle{
    background: rgba(255, 255, 255, 0);
}
.catListTitle{
    background-color: rgba(33, 160, 139, 0);
}

.catListTitle {
    background: rgba(51, 153, 0, 0);
    border-bottom: 1px solid #006600;
    border-top-left-radius: 7px;
    border-top-right-radius: 7px;
    color: rgba(37, 177, 80, 0.61);
    font-size: 1.3em;
    height: 1.8em;
    line-height: 1.8em;
    padding: 6px;
    text-indent: 0.6em;
    text-shadow: 0px 0px rgba(0, 0, 0, 0.3);
}

#topics{
    background: rgba(255, 255, 255, 0.5);
}

.c_ad_block{
    display: none;
}

#tbCommentBody{
    width: 100%;
    height: 200px;
    background: rgba(255, 255, 255, 0.5);
}

#q{background: rgba(255, 255, 255, 0);}

.CalNextPrev{background: rgba(255, 255, 255, 0);}

如果想更改圖片請找到

body {
    background-repeat: no-repeat;  
    background: rgba(12, 100, 129, 0) url('http://images.cnblogs.com/cnblogs_com/LYFmobai/1353819/o_you.jpg') fixed;
    background-position: 100%  50%; 
    background-size: 50% auto;
}

這裡的第二行 url後面有網址 ， 把自己的要的圖片弄到部落格的相簿

你add了你的圖片後 

找到 Original Image

然後點一下就有地址了。

然後你再url的後面就可以了

關於大小： body 最下面有個

background-size: 50% auto;
你可以調一下（我也不太懂 ， 可以直接百度一下）
還有一個 注意一下面板要選darkgree...