I am well into my income section. How can I go back into the section were to add more T3 and T5008

You can use the "Find" tool in the upper right to search for those forms and go to them directly.  For example, click on “Find”, search for “T3”. Select “T3 – Mutual Fund/Trust Income Allocations and Designations” in the list and click on the "Go" button. You can then click on the “Enter New T3 for [NAME]” to add another T3 slip.