The Open or Fold tool can be used for both cash games and no-limit hold'em tournaments. For your tournaments, you'll find a box to indicate the antes in effect in your tournament at a given moment in the game (antes will be expressed as a percentage). The tool is also useful for regular cash games (regular cash games are cash games in which your stack is 100 big blinds). This is also known as "full stack" play.
Please note that this page applies to 6-max games only. If you're at the final table of a tournament and there are only 6 players left, this tool is not recommended and you'll have to look at the ICM calculators instead. (see here https://www.push-or-fold.com/icm.php).
As you'll see, this tool is very simple and intuitive to use. The result you'll get will be the GTO (Game Theory Optimal) opening, i.e., the optimal strategy, the one that can't be exploited. Of course, without going into too much strategic detail, you can modify the strategy slightly according to the behavior of the players at your table. To give a simple and precise example, if you're wondering whether your open button with AT is profitable, and the tool tells you that it is, even though A9 and A8 are not recommended, but your table is very tight and the players are folding a lot, it's a safe bet that you can profitably go slightly outside the optimal strategy by opening a little wider with your A9 and A8.
If applicable, enter the antes in effect at your table (for tournaments only).
If you're playing cash games, don't enter anything. Antes are important to calculate, as the optimal strategy will always be a little more aggressive when antes are present. When antes are introduced at the table, no more hands are free, as is the case in cash games for example (where the only forced bets will be the small and big blinds).
Select your two cards received preflop, specifying whether or not they match (same suit).
There won't be a huge difference between, say, offsuit AT and suited AT, but as poker is a game of details, it's best to be as precise as possible.
Indicate your position on the table.
It goes without saying that the "later" your position, the wider you'll be able to open. One reason for this is that there will be fewer players left to talk to if you're in the dealer position than in the Under The Gun (UTG) position, where you talk first preflop.
Indicate your number of blinds.
The more blinds you have and the earlier in the hand you open, the more conservatively you should play. Conversely, the later in the hand and the fewer blinds you have in a tournament, the wider you can open. Think about the fact that if you're in a tournament and have few blinds, it's better to push all in than to open. For example, if you have 8 blinds in button position and all the players have folded before you, you'll be better off adopting a push-or-fold strategy rather than opening. With 8 big blinds, you'll never open and then fold. Therefore, it's best to maximize your fold equity by pushing all in rather than raising in the conventional way. For more details on this subject, please consult the following page: https://www.push-or-fold.com/range-push-6-max.php
When you're done, click on "Open". It's that easy!
You will then obtain your result: