Fertility clinics (low sperm)

hi guys, 

need some information.. i went to the gp yesterday to see our results.. and doctor says that my transvagina result is normal, and my husband sperm low mobility (agglutination is low).

and doctor said we make a letter to go to fertility clinic.. 

what we need to do in fertility cliniC?

and its bad if my husband sperm are low? Even doctor said only need 1 sperm to have a baby.. 

need advice please:(