Lower Intermediate - Buying a toothbrush

اعتقد ساذهب الي دكان و اشةري جديد فرشات اسنان كهرباءية كذالك

ha ha ha, we made publicity for the product so you wanna buy one now :) .. By the way, we said (furshaat asnaanفرشاة أسنان) is feminine so the description should be (jadeedah جديدة) instead of(jadeed جديد), so your sentence then should be (أشتري فرشاةأسنان كهربائية جديدة)

shukran, also should i have written ila al dukan
insead of ila dukan

You can say (ila dukkaan), but the meaning wiمl be (to a shop), if you've said (ila aldukkaan) then the meaning will be specifying certain shop (to the shop).
Here is your sentence rewritten with corrections:
أعتقد أني سأذهب الى الدكان و أشتري فرشاة أسنان كهربائية جديدة كذلك

thanks

thanks thanks thanks for your lessons