You could say "Entonces tomo una ducha" or "entonces ducharme".
'To shower' in Spanish is 'duchar.'
You say it "Estoy a punto de tomar una ducha."
Quiero tomar una ducha
You say to them hey take a shower with me :p
"Adios por ahora porque me voy a dar una ducha"
porque no necesito ducha
The word for shower is Ang Ahp Nahm. To take a shower is to By Ahp Nahm.
Most native English speakers say "take a shower" instead of "have a shower." There are circumstances where you can use either, but "take" is probably the safer choice if you're not sure. If you're referring to a shower that's already happened, it doesn't matter so much; "had a shower" and "took a shower" are both fine.
"Ducharse" means "to shower (oneself)" in Spanish
"Do not use the bathtub or the shower" in Spanish is "No use la Tina o la ducha". It is pronounced "No OOH-say la TEE-na oh la DO-cha". Please see the Related link below for confirmation of the translation.
nececitas bañarte = you need to bathe
"Take a shower" in Polish is "weź prysznic" (imperative) or "wziąć prysznic" (infinitive).