I have a dodge ram 1500 that coming out of first gear does not want to change into second gear what do I do?

Service transmission fluid and filter and add a qt of lucas transmission treatment.

I agree with tuff. Also according to the year model could have a solenoid going bad in the transmission. If yours is one of these and you take it to get the fluid and filter changed might want to have the transmission tech to check the solenoids for you.

common with r45 46 may need control pressure regulator [in valve body] also relay in box under hood must have 12 volts, how's the battery ?