Minecraft zap hosting server to execute commands?

I'm new to the field and wanted to spontaneously rent a server to play with my friend. The question is very stupid but how can I go into the gamemode or Admin, etc. By commands in the console, I have already entered it, of course, that I have entered it wrong, but then there's always that it does not work. Does anyone have tips, etc?

/ op [player name]

/ gamemode 1 [player name]

since 1.13

/ gamemode creative [player name]

So in the server console you have to leave the "/" (slash) sign in front of the commands.
To become Admin (OP operator) you need to use the following command

/ op [Nickname]

The following command is used to switch to creative mode:

/ gamemode creative [nickname]

The [] brackets but from the commands omit the service here only for better representation.