You have just chosen WordPress theme for your blog and you need to insert script in to it. Your installed theme doesn’t allow you to put script. Thinking if you can put script in WordPress pages or you have seen other WordPress blog has script inserted in to pages and you know there is really some way to do so but looking How to put script to WordPress blog.
You can insert script, if you are trying to put it through Appearance-Theme options then it is not supported, you can do it with Plugins on side bar. Not all but some theme allow many options to insert in to site pages. If your theme has feature to add ads on many places advertisement 1, advertisement 2….7, advertisements on first post loop, advertisements on single page top, advertisements on single page footer, advertisements then installed theme would not support it but has given option to do same through ShortCode plugin.
What should I do?
Get WordPress Plugin called ShortCoder stores HTML, JavaScript and other snippets in it. You can create short code for scripts and given short code, use this code anywhere in the page this short code get executed in that page.
How to create it?
There is title text box and content text-area to put your script. Give name your shortcode I use addthis to explain it.
1. Create a shortcode named googleanalytics in the Shortcoder admin page.
2. Paste the code in the box given and save it.
3. Use created code in your posts and pages.
4. Now your ad appears in the post.
You create short code and want to delete one or more short code created by shortcoder you are not using any more, go here to know How to delete short codes created by ShortCoder