Just wash it?

Ok, you asked how. Inspect the clothes whether there are any stains on them that ought to be pre-treated. Especially blood is important – never ever treat blood stains with anything but cold water and a lot of soaking time. Hot water and chemical agents will burst the erythrocytes, and the hemoglobin will bind to the fibres. You’ll have to bleach the cloth to have a chance get rid of the stain. Cold water will just dissolve the blood cells, and the stain is gone for good. For other stains, consult the search engine or AI oracle of your choice.

For the actual washing, you’ll need some kind of detergent and warm water. 30–40° C (about 90–110° F, I suppose) is hot enough, so as long as you’ve got hot water from the tap, just use that – as hot as you can comfortably stick your hand in. Let chemistry do the grunt work by letting the clothes soak for about an hour in water + detergent. Then take them out of the water and press the water out of them – there are a few techniques to do these, like wringing, twisting and paddeling (yep, paddles are originally washing tools, not torture implements). Repeat a couple of times. It might be necessary to change the water if it gets too dirty. Inspect the clothes and treat remaining stains by applying detergent and rubbing them – in former times they used a special washboard, but without one, I’m just rubbing cloth on cloth or use a brush.

Without a centrifuge, it’s pretty hard to get the water out of the clothes. Hand washed clothes will stay pretty wet. Washing just one or two items outside, I’ve got good results by swirling the cloth around with an arm, but that’s not feasible inside or with more than one or two items. You’ll have to hung them on a washing line as wet as they are. Be prepared - depending on your climate, they’ll be dry within no time or two days. If you get a lot of sun, consider to protect your clothes from it - sun’s UV + water produces Ozone, which bleaches everything. That’s the cheapest way to bleach stuff, by the way - just lay the wet cloth in the sun. If you have to hang your clothes indoor, be aware that there is a lot of water in them - if you have to regularily dry clothes indoors, you will get problems with mold, unless you air your dwelling religiously - or live in a very bad insulated building or somewhere where they’ve got these air conditioning thingies. Air drying your clothes will let them pretty stiff and wrinkly compared to dryer drying them, an iron is your friend if that’s too much for you.

Take care of your hands - manual washing wreaks your skin. Use skin cream before and after.