In Counterwallet, pick an address you want to use as the issuing address.
Then in Address Actions for this address select Create a Token (Asset).
After that you can choose if you want to create a Regular or Free Numeric Asset.
As the name suggests, free numeric assets can be created at no cost, while regular assets (tokens) are not (as of now, to prevent “asset spamming” the cost to register a regular asset is 0.5 XCP and that amount is “burned”).