i am on f1 visa and i got an offer for being an instructor but for full time non tenure track in university but it is gonna be per semester,

The instructor position would have to require 4-year degree and you must have the degree that the position requires before you could qualify for an H1B1 visa.  Right now, there are no H1B1 visas available.  They won't open up the numbers again until next spring.  So you wouldn't know whether you get one of the available visas until later in 2013.  Often, that waiting period makes changing to H1B1 status a difficult task.