Call Cleveland approach, give your call sign, position, and altitude. When they reply, tell them your destination and that you would like flight following, They will assign you a transponder code. When you have your destination in flight, request to end radar service and to change frequency.
So it might go like this:
"Cleveland Approach, Cessna niner alpha mike foxtrot, 5 miles north of somewhere, 2500.
"9AMF, go ahead"
"Cleveland, 9AMF is en-route to somewhere else, requesting flight following"
"Roger 9AMF, squawk 3456"
Keep in mind that VFR flight following is on a time permitting basis - you still need to scan for traffic, navigate, etc. It is also not a clearance to enter class B airspace.
When you have the destination is sight:
" Cleveland, Cessna 9MF would like to terminate flight following and change frequencies."
"Roger 9AMF, radar service terminated, squawk 1200, frequency change approved"