Needing help using the "Sed" function in unix.

Using Sed 1) What do you type in order to substitute all occurrences of the word "crow" with the word "blackbird" in the file misc_mammal_and_bird_genes.fasta and output the result to a new file called misc mammal and bird genes blackbird.fasta? 2) What do you type in order to substitute all occurrences of the word "proinsulin" with the word "Insi" in the file misc_mammal_and_bird_genes.fasta and send the output to a new file called misc_mammal_and_bird_genes_editedi.fasta? 3) Now, use a pipe to combine the sed substitution from question #1 with the sed substitution from #2--do both changes to misc_mammal_and_bird_genes.fasta and write out the result to a new file called two changes.fasta