El sábado asistiré a un seminario y recibiré un ejemplo práctico de programación.

The verb asistir requires the preposition a when you say what you’re attending.
Example:

• asistir a una reunión (to attend a meeting)
• asistir a la clase (to attend class)

In Spanish you normally use the definite article el before days of the week when talking about something happening on that day (especially for upcoming events).

• El sábado voy al cine. (On Saturday I’m going to the movies.)
  You can drop el in casual speech if you mean “this Saturday” or when you use the day as an adverb:
• Sabado voy al cine (less formal, but more common is still El sábado).

You take the infinitive (e.g., asistir, recibir) and add the endings:

• yo –é
• tú –ás
• él/ella/usted –á
• nosotros –emos
• vosotros –éis
• ellos/ellas/ustedes –án
  So asistir + é = asistiré, recibir + é = recibiré (“I will attend,” “I will receive”).

Both are correct:

• Asistiré = simple future, often more formal or expresses a firm intention.
• Voy a asistir = periphrastic future, common in spoken Spanish for near-future events.
  You can choose based on style or emphasis:
• Asistiré al seminario el sábado. (a bit more formal)
• Voy a asistir al seminario el sábado. (very normal conversation)

Spanish descriptive adjectives typically follow the noun:

• un ejemplo práctico (a practical example)
  Putting práctico before (un práctico ejemplo) is grammatically possible but unusual and may sound poetic or emphasize “práctico.” Standard word order is noun + adjective.

Here de links two nouns, showing a relationship or category.

• ejemplo de programación = “example of programming”
  It’s like English “programming example.” The structure is [noun] + de + [noun].

Spanish nouns are almost always accompanied by an article when singular and countable. English sometimes drops “a,” but in Spanish you need un (masculine singular):

• un seminario (a seminar)
• un ejemplo (an example)

Spanish verb endings indicate the subject, so the pronoun is optional and usually dropped unless needed for emphasis or clarity.

• (Yo) asistiré a un seminario…
  Including yo is not wrong, but it’s redundant because –é already tells you the subject is “I.”