Hello Nataliia,
Thanks for using Wazuh!
In order to collect logs from custom log files, you need to make use of Wazuh's localfile (log collector) module.
You can find related information here: https://documentation.wazuh.com/current/user-manual/capabilities/log-data-collection/how-it-works.html#log-collection
And here's an example of such module:
This module would ingest all events contained in C:\logtest\log.txt. Make sure to set it up inside the <ossec_config> tags.
Also, most probably you will also need to create some custom decoders and rules for your events.
I hope this helps! Let me know how everything goes!