Instructions
Close your ̶0;Minecraft̶1; server if it is currently running and open the server folder.
Double-click on the ̶0;ops̶1; text document and type your ̶0;Minecraft̶1; user name into the first line of the document. If there are other players you want to change the rank for, type their user names into separate lines in the document.
Save the text document and start your ̶0;Minecraft̶1; server again. Each player you added to the text document, including yourself, will now have the ̶0;Operator̶1; rank on your server. This means they will be able to enter commands into the game to generate materials.