The rpm command cannot be used ~~~

The rpm command cannot be used ~~~ -- Linux general technology-Linux technology and application information. For details, refer to the following section. [I = s] This post was last edited by lyl-0625

When I install the rpm package, the input rpm command cannot be installed ~~~
The command entered is correct, my downloaded package is xmms-1.2.8-1.i386.rpm
Then enter the command: rpm-Uvh xmms-1.2.8-1.i386.rpm to install,
However, the following information is displayed after you enter the command:
Xmms ~~~ V3 DSA signature: Nokey, Key ID e42d547b

Error: cannot get exclusive lock on/var/lib/rpm/packages
Error: cannot open packages index using db3 -- operation not permitted
Error: cannot open packages database in/var/lib/rpm

According to the information I collected on the internet, it seems that I have not installed yum.
However, I don't think I can understand the prompts on the Internet. Can I submit some easy-to-understand methods for installation.
I am using redhat 9.0 and use a virtual machine to install it ~~~ Thank you.