My car will start/turn over but wont move?

What is your question?

my car will start, but when i shift it out of park it will raise the RPM and will rev up but wont actually move the car. The sensor and linkage for the transmission has been changed but we cannot figure out the problem and cannot pay to have it worked on with 4 kids under the age of 4 and i just bought this car 3 months ago. HELP!!!