Before rebalancing your portfolio, you need to learn how to create it. Detailed instructions can be found under this link: HERE.
Once your portfolio is created, please go to a "My Portfolios" tab on upper menu.
Select a portfolio that you want to rebalance. Click on "REBALANCE".
In the 1st step, "Assets", Add or remove crypto currencies in the portfolio by selecting them from the given list. Click "Next".
In the 2nd step, "Confirmation", the window shows pie charts with currencies entering the portfolio before and after rebalancing.
Click on "Rebalance" to make changes in the portfolio. You may continue to rebalance your portfolio as many times as you want.
After the portfolio rebalancing is completed, you will be redirected to the "My Portfolios" page.