Extract the file to downloads folder. Then open TXD Tool and open gta3.txt and import the image files you extracted (when importing choose Uncompressed 32bpp). Then check where it says Overwrite and click Ok. Wait for the import to finish and you are done. I've added some screenshots as an example. If you want a texture mod that is not available for android but it is for PC, just open the TXD file and export the images so you can import then to your android game version. For example if you want effects you needto open EffectPC.txd with TXD tool. Also copy effects.fxp to Android/data/com.rockstargamesgtasa/files/texdb/models. Then tap on 3 dots and click export. Then just open txd.txt and click select from images and import it. That's it.