If you are having difficuty at this stage I seriously suggest you check out a couple of books (there are many) from your public library on family history - also many Local Authorities run short intro courses - also there are many Fam History magazines that usually include a beginners start here section.
For Manx records you can use the following
Post 1911 - www.manxbmd.com has index pages to the BirthDeaathMarriage certificates buyable from IoM General Registry - also the some of the Manx newspapaers are now online - look at other threads on this page
1841-1911 - the decennial census allows to back trace ancestors - buy it on cd (about £15/census), subscribe to something like ancestry.com or ask at your local library - back these entries with the entries found in the IGI www.familysearch.org (+ especially their new beta site) - also from about 1800 Memorial inscriptions play a key role - ask re these on this board - the burial index (look at www.iomfhs.im is a key resource)
1700-1800 Wills and Parish records are you key source with land records becoming increasingly important as you move back - there is an index to wills on www.iomfhs.com + high % summarised on Manxnotebook - Marriage contracts are also useful
pre 1700 - some wills but generally land records