Thank you ATpoint.
I did run source ~/.bash_profile and it didn't say anything wrong in the Terminal.
I tried to list what it contains in the folder:
(base) mean-machine:bwa-0.7.17 Admin$ ls
COPYING bwa.h bwashm.o bwtsw2_aux.c kopen.o maxk.c
ChangeLog bwa.o bwt.c bwtsw2_aux.o kseq.h maxk.o
Makefile bwakit bwt.h bwtsw2_chain.c ksort.h pemerge.c
NEWS.md bwamem.c bwt.o bwtsw2_chain.o kstring.c pemerge.o
QSufSort.c bwamem.h bwt_gen.c bwtsw2_core.c kstring.h qualfa2fq.pl
QSufSort.h bwamem.o bwt_gen.o bwtsw2_core.o kstring.o rle.c
QSufSort.o bwamem_extra.c bwt_lite.c bwtsw2_main.c ksw.c rle.h
README-alt.md bwamem_extra.o bwt_lite.h bwtsw2_main.o ksw.h rle.o
README.md bwamem_pair.c bwt_lite.o bwtsw2_pair.c ksw.o rope.c
bamlite.c bwamem_pair.o bwtaln.c bwtsw2_pair.o kthread.c rope.h
bamlite.h bwape.c bwtaln.h example.c kthread.o rope.o
bamlite.o bwape.o bwtaln.o fastmap.c kvec.h utils.c
bntseq.c bwase.c bwtgap.c fastmap.o libbwa.a utils.h
bntseq.h bwase.h bwtgap.h is.c main.c utils.o
bntseq.o bwase.o bwtgap.o is.o main.o xa2multi.pl
bwa bwaseqio.c bwtindex.c kbtree.h malloc_wrap.c
bwa.1 bwaseqio.o bwtindex.o khash.h malloc_wrap.h
bwa.c bwashm.c bwtsw2.h kopen.c malloc_wrap.o
(base) mean-machine:bwa-0.7.17 Admin$
As you can see, these is a "bwa" in the list, but I couldn't found in the folder. By the way, the folder I placed on the desktop.
What can I do to add "bwa" to the PATH? Sorry, the question is so stupid, but I just know very little about computer and computer programming.