Penci Design replied
Hi,
1/ With Archive, Category, Blog, Tag, Search Pages
Please go to Customize > Archive, Category, Blog, Tag, Search Pages Options
then make sure that you use layout two sidebar http://prntscr.com/ndqzyt
and check sidebar you use on left and on right content of category page http://prntscr.com/ndr0j2
then go to Dashboah > Appearance > Widgets then add widget to sidebar you choose on customize as screenshot http://prntscr.com/ndr1gv, http://prntscr.com/ndr1or
2/ With single post, please go to Customize > Single Post options then make sure that you use layout two sidebar
Please checkthis guide to know How to Add and Use Widgets in WordPress
Best Regards,
PenciDesign