1. Sort by variables you'll be merging on
2. Merge via data step or SQL
Before you do, consider what type of merge you want. Is this a one to one match - each record in table 1 has an exat match in table 2?
Or do you want all records from one table? What if there's no match?
The documentation is very helpful in walking you through a merge and multiple different types of combining data. Here's the link to the Match Merge docs.
http://support.sas.com/documentation/cdl/en/lrcon/68089/HTML/default/viewer.htm#n1tgk0uanvisvon1r26l...
proc sort data=data1; by company_name year;
proc sort data=data2; by company_name year;
data want;
merge data1 data2;
by company_name year;
run;