I recommend you download the SD Manual here
(click on the 'SkyDemon User Manual' link) and read from page 46. The manual is updated after each software update, so it's worth keeping an eye on this to make sure that you always have the latest version downloaded.
You DO NOT need to have a route plotted. On your PC, having right clicked on the airfield of interest on the chart, you only have to hover the mouse pointer over the airfield name in the list that appears in order to open another list of options, of which one such option is Find Plates. Click on this option and a list of available plates will appear under the Airfields Tab at the bottom right-hand corner of the screen (assuming that you've downloaded them already).
I DONT get the tab selection on right side of map.
I think you may be referring to the tabs on your tablet. Is this correct? If so, just tap on a tab to undock it. Tap it again to re-dock it, or tap the back button. These tabs will only populate once you have planned a route.
I hope this helps, but please don't hesitate to come back to me if you need further assistance.
Nexus 7 (2013) – Android 6.0.1 & SD 220.127.116.1113
Huawei P30 – Android 9.1.0 & SD 18.104.22.168.25213
PC – Windows 10 (Home Ed) Version 1903, Build 18362.449 & SD 22.214.171.124