Where to go from here
Once you have both your CCNA in routing/switching (which is the prerequisite for CCNA Security), and then taken and passed the CCNA Security as well, you will have a solid networking foundation to grow from. One possible next step would be to obtain an additional CCNA certification in Voice or Wireless. Other options include building upon current knowledge and continuing on to Cisco certified network professional certification (CCNP) in routing/switching or the CCNP for security. The path you choose may be influenced by your interest in a specific technology, or perhaps based on what your current job responsibilities and or goals are.
Thanks for reading, and may you have the best of success in realizing your goals.