1. Start GenomeMapping application. 2. Select [Function] → [Trimming]. 3. Click [Add] button of 'Input Files'. 4. Select input file and click [Open]. 5. Click [...] button of 'Output File'. 6. Input filename and click [Save] to decide. 7. Move to 'Trim' tab. Check 'Trim by poly-A(T) tail' and 'Trim by Quality'. 8. Move to 'Reject' tab. Check 'Reject Short Sequence' and 'Reject Ambiguous Sequence'. 9. Click [OK] button to start analysis. 10. Trimming results are generated.