1) select a bloom that is somewhere between a day from opening and just barely open.
2) remove the petals.
3) select a container to hold the anthers in while they dry. Many people use empty baby food jars.
4) remove the anthers from the bloom either with tweezers or a pair of scissors, dropping them in the jar.
5) allow the anthers to dry in a warm, dry place (out of direct sunlight) for 24 hours.
6) shake the jar to dislodge the pollen from the dried anthers. At this point you should have plenty of pollen in the bottom of the jar, ready to use.

PS: its probably too late to mature a crop of Hybrid Tea seeds in your climate zone. You need to start earlier than July if you are going to get properly ripened seeds.

After Paul's step 6, sometimes you have to crush the anthers to get them to release the pollen.