To add tabs, simply click on the 'plus' button on the upper right hand side of your portal next to the menu. You can also rearrange tabs by simply dragging and dropping it to where you would like to position it.
To customize your tab settings, click on the gear icon on the lower left side corner of your portal. Under the tab settings, you can rename, set your tab as draft while you are still building it and set tab access to either a group or individual users to limit the people who can see all the information on a specific tab.
More about tab access setting here.
Before you jump in to adding content, you must add rows first. Simply click on the '+' sign at the lower left hand side and click on the row icon. There are three row types you can add: a row divided in three columns, a row divided in two cols of same width or occupying respectively 2/3 and 1/3 of the tab width or vice versa and a row of four cols. Rows can be rearranged by dragging and dropping it to where you want it to be.
There are two type of content you can add to your Portal: Podio contents and standard contents
To know more about each field, go here.
Get to know more about these fields, see this article.
Each content added in a row can be dragged in itself or from one row to another but some contents are only accepted in an enough large column according to row chosen by the user such as app view or podio webform for example. Also, each content has its own settings that can be modified on edit mode by just clicking on the edit button.