Logged in as a Site Admistrator:
1. Click Site Actions
2. Site Settings
3. Under Look and Feel> Save Site as Template
4. On this screen >
Fill in File name (Keep it short, no spaces, single words works best)
Fill in Template Name (this can be more descriptive, but still keep it short 2 - 3 words)
Template Description (here you can go more into detail about your template)
Include Content (use this only if you have custom lists, workflows, content types etc to reuse)
Including content makes your template larger.
(If using including content try to do so before adding data unless necessary or you will be removing data every time this is deployed)
5. Click OK and Success! You can now use it