بعد أن أغسل وجهي، أضع المنشفة على وجهي.

بعد أن is a very common way to say after + a full clause.

• بعد = after
• أن introduces a verb clause

So:

• بعد أن أغسل وجهي = after I wash my face

This is different from using بعد with a noun or verbal noun, for example:

• بعد غسل وجهي = after washing my face

Both are correct, but بعد أن + verb is often easier for learners because it works like a full English clause.

In Arabic, the present tense often describes:

• habitual actions
• general routines
• step-by-step actions
• instructions

So this sentence sounds like a routine:

• بعد أن أغسل وجهي، أضع المنشفة على وجهي.
• After I wash my face, I put the towel on my face.

It does not have to mean the action is happening right now. It can mean whenever I do this, or this is what I do next.

If you wanted a one-time past event in a story, you would normally use past verbs instead, such as:

• بعد أن غسلتُ وجهي، وضعتُ المنشفة على وجهي.

Yes. After أن, the present tense verb is normally in the subjunctive.

With full vowel endings:

• indicative: أغسلُ
• subjunctive after أن: أغسلَ

But in normal Arabic writing, short vowels are usually not written, so both simply appear as:

• أغسل

That is why you do not see a spelling change here, even though there is a grammatical change.

وجهي means my face.

It is made of:

• وجه = face
• ـي = my

So:

• وجه → face
• وجهي → my face

This attached ـي is a possessive suffix. Arabic uses these attached endings very often:

• كتابي = my book
• بيتي = my house
• وجهي = my face

Arabic often repeats a noun for clarity, especially when a pronoun could be confusing.

So:

• بعد أن أغسل وجهي، أضع المنشفة على وجهي.

is very clear.

If you replaced the second وجهي with a pronoun, you might get:

• أضع المنشفة عليه

Grammatically, that means I put the towel on it / on him, but it is less clear what ـه refers to. Repeating وجهي avoids ambiguity and sounds natural.

على usually means on or onto.

So:

• أضع المنشفة على وجهي = I put the towel on my face

It is the natural preposition for placing something on the surface of something else, including a body part.

Compare:

• على = on
• في = in
• إلى = to / toward
• فوق = above / over

Here, على is the best choice because the towel is being placed on the face.

المنشفة means the towel.

Arabic often uses the definite article الـ when the object is specific, known from context, or understood in a routine situation. In this sentence, it sounds like a particular towel that is being used as part of the action.

So:

• المنشفة = the towel
• منشفة = a towel

Both can be grammatical, but المنشفة sounds more like the towel I use / the towel in this situation.

It is natural if you literally mean I place the towel on my face.

However, if you mean I dry my face with the towel or I wipe my face with the towel, Arabic often uses a more specific verb, such as:

• أمسح وجهي بالمنشفة = I wipe my face with the towel
• أجفف وجهي بالمنشفة = I dry my face with the towel

So the original sentence is correct, but a native speaker might choose a different verb depending on the exact action.

Yes. Arabic allows some flexibility.

These are both correct:

• بعد أن أغسل وجهي، أضع المنشفة على وجهي.
• أضع المنشفة على وجهي بعد أن أغسل وجهي.

The first version emphasizes the time sequence right away: After I wash my face...

The second version starts with the main action first: I put the towel on my face after I wash my face.

Both mean essentially the same thing.

Yes, often you can.

For example:

• بعدما أغسل وجهي، أضع المنشفة على وجهي.

In many contexts, بعدما and بعد أن are very close in meaning. For a learner, بعد أن is often easier to analyze because you can clearly see:

• بعد = after
• أن = clause marker before the verb

So even if both are possible, بعد أن is a very useful pattern to learn early.