You can upgrade your account be clicking on the purchase option in the top menu. This will take you to a page where you can select to upgrade your membership or buy tokens.
Upgrading Your Membership
Before you can start new conversations you first need to upgrade to a premium membership. You can do this be selecting the plan and pressing the checkout button.
Buying Tokens
Some features of the dating site requote the use of tokens. You can buy extra tokens by clicking on the token option which can be found on the purchase screen. Then you will see the token plans you can purchase.