Hi Merlinmartel, and welcome to Wikipedia! I apologise for not leaving you a message when I reverted your edit. I usually try to do that, especially when it's a new editor - Wikipedia has a lot of rules and I know it's easy to get a bit lost among them all.
In the case of Comparison of project management software, that article compares software products that have a Wikipedia article. If you look at the list, you'll notice that all the entries are blue links, meaning that there is an article there. The entry you added was a so-called "redlink" - there's no article about UManage and so the link shows up as red.
When you edit Comparison of project management software there's a note at the top of the edit box that says "Only place entries here that are links to actual Wikipedia articles about notable project management software. External links, redlinks, non-notable sites or sites that are not project management software will be removed. If you have questions, use the talk page." This is something that is usually the rule for list articles on Wikipedia, and it's done in order to make sure that the entries are all notable (according to Wikipedia's definition of notability).
If you want to create an article about UManage, I recommend that you use the Article wizard which guides you through the various steps that are required. Before that, however, you might want to read this information about creating your first article, which might help you determine whether UManage is in fact notable enough for its own article.
Feel free to post to my talk page again if you have more question, or go to the teahouse, where many experienced editors respond to all kinds of questions about editing.
Regards, --bonadea contributions talk 19:48, 9 January 2015 (UTC)