MyHeritage provides tools for you to research your family tree similar to other family tree sites. If you want assistancen in researching your family tree, three is a link to "Hire a researcher" under the Research dropdown.
If you want to do it on your own, you will find hat MyHeritage can help you trace your roots if you provide sufficiant information to get it started. Generaly you need to supply information about your relative back several generations. The latest publically available US Census data is 1940 so you need to have information in your tree that includes ancestors alive during the 1940 census.
I have found that the search is a lot of fun and have discovere lots of surprising information about my ancestors such as Civil war service and injuries as well as one line that most of the family were killed in an indian raid. Fortuantely (for me) my ancestior from that family had married and moved away from the area.