Below is an example of rebalancing a Portfolio that follows a model. The operation of "rebalancing" is needed when your portfolio is drifting (expressed as a percentage) from the underlying model. In this particular case the positions are different which is why the current drift cannot be calculated.
Rebalancing with TRADE is a single click operation. You can also override the suggested rebalance by excluding certain transactions, change the number of shares and select the order type.