1)if the weather (be) fine, we (go) for a walk 2)if i (have) money? i (buy) this dress 3)if my mum (bring) a cake, i (invite) my friends 4)if i (be) you , i (go) to the doctor 5)if she (call) you, she (fell) you everything надо поставить в conditional 2 и 3 каждый

Нужно преобразовать каждое предложение в Conditional 2 и Conditional 3.

Сначала коротко напомню разницу:

• Conditional 2 — нереальная или маловероятная ситуация в настоящем или будущем.
  Формула: If + Past Simple, would + V1

• Conditional 3 — нереальная ситуация в прошлом, то есть то, что уже не произошло.
  Формула: If + Past Perfect, would have + V3

Теперь каждое предложение.

1) if the weather (be) fine, we (go) for a walk

Conditional 2:
If the weather were fine, we would go for a walk.
Перевод: Если бы погода была хорошая, мы бы пошли гулять.

Conditional 3:
If the weather had been fine, we would have gone for a walk.
Перевод: Если бы погода была хорошая, мы бы пошли гулять.

2) if I (have) money, I (buy) this dress

Conditional 2:
If I had money, I would buy this dress.
Перевод: Если бы у меня были деньги, я бы купила это платье.

Conditional 3:
If I had had money, I would have bought this dress.
Перевод: Если бы у меня были деньги, я бы купила это платье.

3) if my mum (bring) a cake, I (invite) my friends

Conditional 2:
If my mum brought a cake, I would invite my friends.
Перевод: Если бы мама принесла торт, я бы пригласила друзей.

Conditional 3:
If my mum had brought a cake, I would have invited my friends.
Перевод: Если бы мама принесла торт, я бы пригласила друзей.

4) if I (be) you, I (go) to the doctor

Это классический Conditional 2, потому что выражение If I were you используется для совета.

Conditional 2:
If I were you, I would go to the doctor.
Перевод: На твоем месте я бы пошла к врачу.

Conditional 3:
If I had been you, I would have gone to the doctor.
Грамматически такую форму можно построить, но в реальной речи так почти не говорят, потому что “If I had been you” звучит неестественно. Для школьного задания как форма Conditional 3 она возможна, но обычно используют именно If I were you.

5) if she (call) you, she (tell) you everything

У тебя в вопросе, скорее всего, опечатка: не fell, а tell.

Conditional 2:
If she called you, she would tell you everything.
Перевод: Если бы она позвонила тебе, она бы рассказала тебе всё.

Conditional 3:
If she had called you, she would have told you everything.
Перевод: Если бы она позвонила тебе, она бы рассказала тебе всё.

Итоговый вариант:

1. If the weather were fine, we would go for a walk.
   If the weather had been fine, we would have gone for a walk.

2. If I had money, I would buy this dress.
   If I had had money, I would have bought this dress.

3. If my mum brought a cake, I would invite my friends.
   If my mum had brought a cake, I would have invited my friends.

4. If I were you, I would go to the doctor.
   If I had been you, I would have gone to the doctor.

5. If she called you, she would tell you everything.
   If she had called you, she would have told you everything.