Typo3 content elements provide an option to automatically present a link back to the top of the page.
To ensure this works also with optimized urls (e.g. cooluri) and configurations which clean up your html output, you can use the following setting in the typoscript setup of your template:
prefixLocalAnchors = all
Furthermore, you can manipulate this link with the stdwrap setting as presented below:
tt_content.stdWrap.innerWrap2 = |Bring me back to the top
Typo3: To Top Link