If desired, you can add a link to the birthday modul in the user menue.
Here's step by step how to do it:
1. As an admin go to "System Admin / General Preferences / Blocks"
2. Search for the "Usermenue"
3. Click on "Edit"
4. Click on "Edit Template"
5. At the end of the template, e.g. just before 
<a href="<{$xoops_url}>/user.php?op=logout"><{$block.lang_logout}></a>
add the following line:
<a class="menuTop" href="<{$xoops_url}>/modules/birthday/index.php">My Birthday</a>
6. Save the template
7. Update the "system" module.