Hi Sheila and Welcome,
Can you access the research that your cousin did? If you can get that, you will have a big head start.
The best way to connect on WikiTree is to begin by entering the information you know about yourself, then your parents and grandparents. It is easiest to build a tree up from the trunk and out the branches. As you add more ancestors you will likely find cousins already here and be able to attach your ancestors to theirs. It appears that you have a good start on this already. Keep up the good work.
If you do not have the details, try researching on FamilySearch.org, it is a free resource and has lots of information in an easy to use format.