My transmission isnt acting right its shifting from 1st to 3rd?

my transmission isnt acting right its shifting from 1st to 3rd instead of 1st to 2nd,but i can shift with the gear selector and 2nd gear works fine but if i put it in drive it shifts to 3rd and skips 2nd.. i have a 00 ford ranger the overdrive light flashes when it slams into 3rd