Are you trying to base pair your two nucleotides. If yes, I usually do that by mixing them in a 1:1 molar ratio in PCR buffer (for Taq polymerase), heat them at 94 deg C for 3 minutes and then let the solution cool on the bench till it reaches room temperature. That should work.

look at definition of melting temperature Tm of oligonucleotides and how it is measured and you will get answer