What way(s) can i insert his fresh sperm into my vagina with my fingers, during ovulation, to have a good chance of getting pregnant?

There is no better: way than sex with full penetration, short of artificial insemination. On another note, you are only 18 and might want to wait a little before burdening yourself with a baby. Being a single mother is a major risk for child abuse, poor scholastic performance and other less visible issues

Ob-Gyn fertility: If not by sexual intercourse, some women have had success with a turkey baster so that the sperm is in the cervix. Otherwise, OB-Gyn procedure. Some women also will position themselves such that their pelvis is elevated letting gravity work.