Would someone please explain to me what intermolecular forces are. I don't really understand the whole concept.

2 answers

Dipole attractions, London Forces and Hydrogen Bonding. For details on how they arise and how they compare, consult any chemistry textbook. Check under "intermolecular forces" or the individual names I gave you.
Additional Note:
Intermolecular forces in general are attractions between molecules in a molecular substance. These forces determine physical properties such as boiling point (the stronger the forces the higher the BP), melting point (also the stronger the higher), vapor pressure (the stronger the forces the lower the VP).