my dad cuts it back,but i dont know when,good luck

I wouldn't take any stems of a first year rhubarb and you need rather more than two for a pudding. Pull the stalks in autumn as they start to rot back and compost.

I would just let it die back naturally, as rhubarb is just another herbaceous perennial, which stores all its energy in the roots over winter and this is taken in from the leaves and stems. Don't pull any rhubarb until next year, and then sparingly, until the plant is growing into a good clump. Best time for harvesting is in spring when young, as the later rhubarb has much more oxalic acid in the stems which is not good for you. Rhubarb is a gross feeder so you can tip lots of well rotted horse manure or cow manure on it over winter and it will reward you with lush growth and thick stems.
Best of all, once it is well established, you can cover it with an upturned black plastic dustbin in late January or February and then harvest the beautiful pink, sweet stems which are forced in this way.
Divide your whole plant and make new ones every four years or so to keep them vigorous.

Thank you so much for all your info. I look forward to lots of Rhubarb puds
!