How to calculate mutation rate and mutation sites in a genome using FASTA file? I have 6 viral genome sequences of the same virus and 1 reference sequence in FASTA format.

How I can identify mutations and mutation sites in those genomes using FASTA sequences  but how I can do this for FASTA file?
And how I can identify the mutation rate for one genome?

Background If I've FASTQ file then I'll simply align the reads to the reference and by using variant calling tool I will get the mutate sites
You can still align a FASTA file with a tool like bwa mem ( if they are short reads ) or minimap2 for long reads and run it through a variant caller like freebayes. Alternatively, if you have sufficient reads to create an assembly of all of the genomes, or if they already are you can create a MSA of them using a tool like Cactus (as it is built for genomes) or MAFFT if the sequences are short enough and then use your favorite viewer to find variable sites