Once you have your dog regularly sitting, you will want to be able to give the opposite command of "stand".
Stand is one of the very basic commands that all dogs should know, along with sit and down, so it is definitely worth spending the time with your dog to train this command.
Once your dog is sitting, stand beside it and hold a treat in front of your dogs nose.
As the dog starts to stand to get the treat, issue the command.
This should be repeated until it an be performed without the treat, although you may want to give the treat after the command has been obeyed to encourage good behaviour.
A problem dog owners regularly encounter is dogs that walk forward rather than stand up when they hear the command.
The dog should only raise its behind off the floor and not walk forward.
This may have come about during training if the treat was held too far away from the dogs mouth so it had to walk forward to receive it.
Try practicing the command by holding the treat close to your dogs nose so it has no need to walk forward and you should see better results.
The basic commands should be frequently practiced, as even a well trained dog can forget commands if they are not used often.
As time goes on, you should phase out treats so that they are no longer needed, but always praise our dogs good behaviour verbally when appropriate.