You can use SSMS 2008 installation for SQL Server 2008 R2. However, you can also use SSMS 2012 or even SSMS 2014 to manage SQL Server.

So, I would go ahead with installing the latest SSMS you can find to download (just SSMS).

>Maybe SSMS was not part of the SQL Server installation. So now I found a link to download SQL Server Management Studio 2008 Express.
>But it does not have R2. If I install this SSMS 2008 (without R2) will I be able to use it on SQL Server 2008 R2 Express?
>
>>I am installing SQL Server 2008 R2 Express on customer server. But I don't see anywhere the option for SQL server management studio.
>>
>>The Installation Center has the following items:
>>Planning
>>Installation
>>Maintenance
>>Tools
>>Resources
>>Advanced
>>Options
>>
>>But I can't seem to find SSMS anywhere. Which of the items above should have it?
>>
>>TIA