Using mcp4725 DAC to output fixed frequency for CW IDer

Hello all! I'm looking for any help or suggestions. I'm very new to Arduino and still learning the basics. I'm trying to use a mcp4725 DAC and Arduino mega to generate a fixed frequency sine wave tone(preferably 800Hz but up to 1000Hz is fine) to use as a homebrew CW IDer for a repeater. I have some code but it only outputs around 50Hz. How do I get to the frequency I need? Thanks for any and all help!!