A couple of things:
'stake' is an expression used for spreadbetting and is variable. When you are trading futures there is a fixed amount per point which equals 1 contract. On ES (S&P emini futures) it is $50 per point per contract. Each point is divided into four, so one tick is equal to $12.50.
So if you want to trade at $50 per point you would buy 1 contract, but if you had deep pockets and want to trade at $400 per point, you would buy 8 contracts.
If you are unsure of these things, such as which future to trade, are you really really sure you are ready to trade futures through IB? What have you been trading up until now, and why don't you want to continue trading that stock or future? With respect, it is very foolhardy to try and trade something you're not sure of, which is what your post suggests to me. 😀