Mainly just need help with step one and step 2. What do I use to merge the two s

Mainly just need help with step one and step 2. What do I use to merge the two spreadsheets together and why? Items in step two are under the placement name in the pivot table; Partner C_Mobile In-App_CPM_6_Display is partner C, mobile in apple, cpm, 6, display.
Can you integrate this all into one dataset and show steps and thought process. Thanks