If i blow my nose and get some of it on fingers then wipe vaginal area,can that cause infection?

Unlikely: Germs usually have a specific area they want to attack-- for example a "cold" virus will only attack your nose/throat and will not attack your vagina. It's just not interested to do that. Practicing good hygiene though is always a good idea- and have to point out that females are more at risk for UTIs than males because of the anatomical differences...