A reflexive verb will always have a "se" added to the verb. When you conjugate it, you take the"se" away, and use the appropriate reflexive pronoun before the conjugated verb.
se se This is the same for either él, ella, ud., ellos, ellas, uds.
The verb is conjugated normally, depending on if it is an ar, er, or ir verb, or an irregular or stem-changing
lavarse = to wash yourself
Yo me lavo Nosotros nos lavamos
Tú te lavas Vosotros os laváis
Él/Ella/Ud. se lava Ellos/Ellas/Uds. se lavan
Some verbs can be reflexive if done to yourself, and not reflexive if done to others.
Reflexive verb Not reflexive
Yo me lavo la cara. Yo lavo los platos.
This one is reflexive because you are This one is not reflexive because doing it to yourself. you are doing it to the dishes.
Talking about body parts in Spanish:
When you are talking about doing something with your body, in English you use the possessive adjective (my, your, his, her, our, their), as in "I wash my hands". In Spanish, since you are using a reflexive verb to show that you are doing it to yourself, you do not use the possessive adjective. So you simply say "I wash the hands"
Yo me lavo las manos NOT Yo me lavo mis manos. This last sentence would be grammatically wrong.