You have to concatenate all target genes and then construct the phylogenetic tree. There are many software available for doing this like MEGAX, RAxML etc.
If you want to align and produce a phylogenetic tree, starting from a multi FASTA file containing all the sequences (genes or proteins), you have very good options. I routinely used the web site www.phylogeny.fr where you will directly get the .
If you want to further manipulate the tree you can use additional software such as Dendroscope.