You can, of course.  After you have submitted an entry, you can edit it as often as you want.  To do so, click the title of the entry, and then click the tab "edit".  After you edit your entry, click "submit" at the bottom of the page.

The architects and moderators of iMechanica can also edit your entry. You can view the changes by clicking the title of your post, and then the tab "revisions". If you disagree with the modification, click "revert".