Fortunately, an American bridge player called Sam Stayman developed a bidding convention which allows you to "ask" your partner that question if you need to.
The member area at No Fear Bridge allows you to choose a personalised set of on-screen flashcards. One of the topics you can choose is Stayman bidding practice.
At the time of writing this post up to 24 cards are available. Choose how many you want to work through. Each card has your hand and the bidding displayed. On the reverse you will find the bid you should make and an explanation of why.