You have to read a complete tutorial but:
After installing blast in your computer and saving it in your path;
mi_database.fasta -> (or .faa, whatever)
-o T = save the output
-p T = is this a protein database? T= yes F = False (for nucleotide database)
formatdb -i mi_database.fasta -o T -p T -> You have to make an index from DB, it generates 6 indexes (like mi_database.fasta.psd, etc etc) Run it on command line.
Now you have database correctly indexed and I supossed that your proteins (query) in fasta format.
this is an example of blast, but you can play with the multiple options (https://www.ncbi.nlm.nih.gov/books/NBK279675/);
blastp -query your_query.faa -db mi_database.fasta -evalue 1e-5 -outfmt 6 -out blast_result.txt