I am new at this, so please can you tell me how to learn to write test scenarios for web and mobile MANUAL testing?
To start with manual testing u should thoroughly understand customer requirement. Scenarios are nothing but high level customer business work flows. From one requirement you can derive many scenarios and they may be negative scenario or positive scenario. For example requirement says username text field should accept 10 characters.You derive scenario like username text field should not accept more than 10 characters(-ve) and username text field shlould accept 10 or within 10 characters (+ve)