I want to append lines after a match in a file.

##file name is ssl.conf
##match is this

<Directory "/var/www/cgi-bin">
SSLOptions +StdEnvVars
</Directory>

after above line i need to append these lines

<Directory "/">
SSLRenegBufferSize 26215000
</Directory>

so final results should be like this

<Directory "/var/www/cgi-bin">
SSLOptions +StdEnvVars
</Directory>

<Directory "/">
SSLRenegBufferSize 26215000
</Directory>

######Thank You in Advance

This can be done with sed
As it may not be obvious, here is some explanation.
The substitute option to sed is delimited with colons to avoid having to escape the forward slashes.
The </Directory>$ specifies the line to be matched has </Directory> at the end of the line.
The &\n\n<Directory "/">\nSSLRenegBufferSize 26215000\n</Directory>\n specifies that the replacement string is that which was matched (&) followed by your required replacement interspersed with new lines (\n) as necessary.
The trailing g specifies a global replacement in the file.

If this is what you want, redirect the output from the command to a file.

Thank You for the reply.

I only want to append , I do not want to substitute.

so final output in file should be

<Directory "/var/www/cgi-bin">
SSLOptions +StdEnvVars
</Directory>

<Directory "/">
SSLRenegBufferSize 26215000
</Directory>

####################################################

Use an editor such as vi, which will let you search for the line you want, then add in what you need to.

Edit: See man vi

If the suggested sed solution does not suit you, then this will do a simple append.
Note the use of the -e option to echo and the escaping of the double quote characters.